Endangered Mission Blue Butterflies Reintroductions in SF Continue with Encouraging Results

SF Rec & Park’s Natural Areas program received more endangered butterflies

SAN FRANCISCO – San Francisco Recreation and Park Department in joint efforts with San Mateo County Parks, and Creekside Science Center for Earth Observation to collect more Mission Blue butterflies from San Bruno Mountain in San Mateo County and release them at Twin Peaks in San Francisco.   Scientists and park staff are continuing to reestablish the endangered Mission blue butterfly at its historic home at Twin Peaks Natural Area. The butterflies were first described from historic collections at Twin Peaks, and the site is considered critical to the species’ recovery.  40 males and 20 females are expected to be collected and released from now on until end of the month of May.

“For the past 29 years of efforts to have been extensive efforts maintain and restore Mission blue butterfly habitat on San Bruno Mountain State and County Park since the Habitat Conservation Plan was adopted in 1983.  It is deeply gratifying to see the Mission blue butterfly population reintroduction with habitat management efforts on a nearby iconic San Francisco mountain top.  Humans can help these endangered species recover,” said Sam Herzberg, Senior Planner of San Mateo County Parks.

In order to prevent negative impacts to the San Bruno Mountain population, San Mateo County Parks and Creekside Science Center for Earth Observation only captured 22 pregnant females in 2009 and brought them to San Francisco’s Twin Peaks.  Since then SF Rec and Park’s Natural Areas Program has been monitoring the area to confirm if the butterflies were able to complete their full life cycle: laying eggs, emerging as caterpillars, and pupating into adult butterflies. With such a demonstration positively completed, an additional 60 butterflies were introduced in 2011. More positive monitoring results this spring showed that caterpillars are still munching away on the lupines at Twin Peaks.

“This vital step in the recovery of this endangered creature could never have been achieved without the hard work, planning and commitment of our partners and SF Rec and Park’s Natural Areas Program staff,” said, Phil Ginsburg, SF Rec and Park General Manager. “The success of this project is encouraging, and we look forward to continue our effort of restoring wild habitat in the middle of our urban metropolis.”

“This project is a great example of people finding relatively low-cost, effective ways to manage habitat for rare species. Even in an urban area such as this, there is a lot of low-hanging fruit to reach for in terms of conservation,” says Christal Niederer, a biologist for the Creekside Center for Earth Observation.

Urbanization and the spread of invasive plant species have severely reduced the viable Mission blue habitat within San Francisco.  In 1976, the federal government listed the Mission blue butterfly as an endangered species and granted it special protection under the law. While the initial success in establishment of the Mission blue butterfly on Twin Peaks is encouraging, the status of the population will remain tenuous until the population grows large enough to sustain itself. The project’s goal is to reach population sizes comparable to those observed in the past – on the order of several hundred butterflies during the 1980s.  Larger numbers of butterflies are necessary to avoid a genetic bottleneck from damaging this small, fragile population.

Creekside Center for Earth Observation was founded in 2006 to apply the latest science and technology to address challenging conservation problems. They have led the effort to reintroduce the federally threatened Bay checkerspot butterfly to Edgewood Natural Preserve, and are enhancing several endangered plant species in the Bay Area, including San Mateo thornmint, Presidio clarkia, fountain thistle, and Tiburon paintbrush.

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